Charged carrier transport efficiency and patterned issues in organic semiconductors (OSCs) limit the potential of organic devices toward nanoscale microelectronic and optoelectronic applications. We demonstrate high-performance organic field-effect transistors (OFETs) with mobility of near 2.5 cm 2/Vs using a nanogroove gate-dielectrics accomplished by nanoimprinting technology. Meanwhile, the flow of charged carriers in OFETs prefers parallel the nanogrooves to result in high electrical anisotropic ratio (above 200), thus achieving built-in auto pattern OSC function with nanoscale resolution. In this study, we also investigate the impact of nanostructural surface properties in relation to the mechanism of the pentacene growth, the polymorphism of the pentacene films. Interestingly, the polymorphism transported from the thin-film phase to the bulk phase is significantly affected by the width of the PI-nanogrooves.